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自地震反射共深度点法介绍以来,我们看到界面覆盖的次数继续不断地增多,特别是现在,大部分的海洋地震勘探都采用48道的48次迭加。因为从这种多次覆盖次数中获得了好处,所以共深度点迭加法压制多次反射是最重要的手段之一。对共深度点迭加压制多次波的理论响应曲线的检验表明,增加迭加次数虽然改善了对多次波的压制,但这种改善随着迭加次数不断增加只是对多次波有更高的频率和较大的剩余时差时出现。在迭加次数多于12次时,这种改善只在相对高的频率和较大的剩余时差时出现,而对剩余时差小、频率较低的多次波来说,则没有明显的改善,这里不幸只能看到那些迭加处理后残留下来的东西。冲零或迭加前切除经过一定选择的道(大部分是较近的炮检距道)的简单方法,能够在宽的低频和迭加响应曲线的剩余时差范围内给出平均6到9分贝的改善,在这个范围的局部地方达到9—15分贝的改善。改善的代价是使随机噪声水平增长1—2分贝。只要我们愿意,用数字处理方法很容易在所选择的地震剖面上把不需要的道冲零。这个方法不要求详细的知道多次波的剩余时差,就能够在强多次波成为问题需要应用更高的迭加次数的地方,常规的应用。
Since the introduction of the Seismic Reflective Co-Depth Point Method, we have seen that the number of interface coverage continues to increase, especially now that 48 marine 48-fold superpositions are used for most marine seismic exploration. Because of the benefits gained from this multiple overlay, adding multiple depths to each other to suppress multiple reflections is one of the most important tools. Examination of the theoretical response curve for the total depth of spot plus pressure multiple waves shows that while increasing the number of superpositions improves the suppression of multiple waves, this improvement increases with the number of superpositions but only with multiples High frequency and large residual time difference appears. With more than 12 iterations, this improvement occurs only at relatively high frequencies and with a large residual time difference, while for the multiple residuals with small residual and low frequencies there is no significant improvement, Here unfortunately, you can only see those that remain after the superposition of things. An easy way to nulls or pre-empts a selected channel (mostly the closer offset) is to give an average of 6 to 9 dB over the remaining time difference of the low-frequency and additive response curves The improvement is achieved in some areas of this range by 9-15 dB improvement. The price of improvement is to increase the random noise level by 1-2 dB. As long as we wish, it is easy to nudge the unwanted lanes by zero using the digital processing method on the selected seismic section. This method, which does not require detailed knowledge of the residual time differences of multiple waves, can be routinely applied where strong multiples become a problem requiring higher numbers of iterations.